Current Insights On Treating Second MPJ Dysfunction

If patients with second metatarsophalangeal joint (MPJ) dysfunction experience a delayed diagnosis or misdiagnosis, the condition can become progressively worse and lead to complications. Accordingly, this author discusses issues with second MPJ surgery, the emerging role of plantar plate repair and a suture and button technique that may prove to be beneficial.

The subtle subluxation of the lesser metatarsophalangeal joint (MPJ) is a chronic, slowly progressive, inflammatory condition referred to as predislocation syndrome.1 When it comes to this chronic pain in the plantar forefoot, physicians commonly misdiagnose it as a neuroma, stress fracture or tendonitis, among other things. Patients often describe the pain as a dull, aching sensation beneath the base of the second digit, just distal to the metatarsal head.

Often, patients describe the sense that they are walking on something like a grape. For some patients, it may feel like their sock is bunched up beneath the ball of their foot. Typically, there is no recall of frank injury but often one can identify a change in activity level from a detailed interview. A person may have just begun to exercise to lose weight or recently started a walking program. Perhaps the patient has changed jobs with the new job requiring more weightbearing activity or increased weightbearing on firm or hard surfaces as in industrial work or the like. Perhaps the patient has simply gained much weight over time.

Most importantly, when the physician misses, misdiagnoses or neglects second MPJ dysfunction, it will progressively worsen with repetitive cycling of the joint. The inflammation will persist, the plantar plate and collateral ligaments will wear, and subtle deviation of the digit in the transverse and/or sagittal plane will occur.

While it is understood that the plantar plate is the strongest fibrous structure supporting the MPJs, the collateral ligaments also play a fundamental role in stabilization of the digit. Often, a combination of sagittal plane and transverse plane deformity develops. Although the natural history of progression is well understood, no one can predict just how quickly this deformity will occur. This may be accelerated by the abnormal mechanics associated with hallux abducto valgus, a long second metatarsal or the injudicious use of steroids physicians deliver into and around the MPJ.

It is predictable that with misdiagnosis, physicians often inappropriately select injection therapy and this can promptly bring the deformity to progressive subluxation and even dislocation at the MPJ level. This occurs all too often. Indeed, it is important have a very high index of suspicion for this chronic inflammatory condition. Early identification and prompt stabilization of the joint will definitively slow the progression of deformity if not halt it altogether. Simple things like the metatarsal sling pad can achieve very good success.

When A Prodromal Syndrome Exists With Recurring Pain

Speaking from my personal experience, I have numerous patients in my relatively young practice (13 years) who have never required surgery as a result of this early intervention. Unfortunately, the people who do best are the ones who already have deformity.

Why do I say unfortunately? When people come in reporting symptoms without any evidence of subluxation, a prodromal syndrome or “stage 0” condition may exist. This stage is associated with an insidious onset of pain, which becomes progressively worse and interferes with a patient’s sense of well-being. At this time, the patient usually has not altered his or her activity level, which contributes to an ongoing and increasing inflammatory reaction as repetitive cycling of the joint continues without support or stabilization.

One may identify the condition and educate the patient about the condition at this time. However, without visible evidence of deformity, it is not uncommon for a patient to participate in a conservative care plan only temporarily. After the use of a metatarsal sling pad or other accommodative forefoot device, the symptoms may resolve. Then the negative reinforcement required to remind the patient to continue using the device is gone.

Once symptoms have disappeared, there is little reason to follow up in the office and the digital splints and other devices fall by the wayside. In this subset of patients, it is common to have them return to the office with subluxation of the digit and worse pain. Sometimes a patient will have experienced injection therapy elsewhere, resulting in end stage subluxation if not dislocation of the joint. When this happens, the patient may pursue legal action given the poor outcome and even worse prognosis.

Taking A Fresh Look At Second MPJ Surgery

There are some who believe that the traditional approach to digital surgery is misguided if not backward in logistics.2 The traditional approach has revolved around shortening the digit via arthroplasty or arthrodesis at the proximal interphalangeal joint level.3 The surgeon then uses a stepwise approach to decompress the joint, ultimately releasing the MPJ capsule and stabilizing that with K-wires across the MPJ for three to four weeks. This procedure can be associated with recurrent deformity despite the best surgical and clinical efforts. Complaints of a stiff digit, chronic swelling, ongoing forefoot pain, lateral transfer lesions and the like make digital surgery a risky prospect for some patients.

For some patients, the use of external K-wires is often aesthetically distasteful and poses an increased risk of bone and joint infection. The discussion of the risk of stiff and swollen digits often curbs a patient’s desire to have definitive correction and rightly so.

From the physician’s standpoint, there are a number of concerns with placing a K-wire across the MPJ and residual joint stiffness is among the most frequent complaints. Placing a 1.25 mm hole in the small cartilage surface area of the metatarsal head often irreparably damages the very joint we were trying to repair. Although no one has ever demonstrated the ill effect of this cartilage damage, the natural history of progression of an osteochondral lesion is well understood. In some cases, the chondral defect(s) can remain silent and asymptomatic while others may experience profound joint dysfunction and degeneration.

An alternative consideration for MPJ dysfunction, specifically second MPJ dysfunction, is arthrodesis of the MPJ. By all accounts, arthrodesis has rarely been tested so there simply is not the data to support or promote its routine use as a primary procedure unless no viable alternative is appropriate.4

In cases in which the second metatarsal is long or plantarflexed, and associated with chronic, well localized forefoot pain, then decompression of the MPJ should be the primary procedure. Repairing the primary stabilizing structure of the MPJ (the plantar plate) becomes a mandatory adjunct. If in fact we have the process backwards, we should be decompressing the MPJ as our first maneuver in the stepwise approach to MPJ dysfunction. This may make the routine practice of arthroplasty/arthrodesis nearly obsolete.

Jolly and colleagues popularized the repair of the plantar plate and the procedure has received much attention in the literature ever since.5 Numerous authors have suggested variations in approach to this repair.6 Surgeons generally employ the technique in conjunction with a second metatarsal osteotomy. Weil Sr. and Weil Jr. provided a detailed review of their approach to MPJ pathology.7 They supported the repair of the plantar plate after completing successful shortening of the second metatarsal.

While I was intrigued by the device the authors described for securing suture in repairing the plantar plate, it became apparent that this technique was not a simple one.7 The space available for the repair of the plantar plate is scant and even the most slender of fingers will be challenged by performing the required maneuvers. I have since developed a modified approach to stabilizing the plantar plate and have found it quite rewarding in the few patients in whom I have selected to use it.

Before going into the details of this technique, I submit to you that most patients I evaluate and treat for MPJ pain and dysfunction recover from their symptoms and impairment very well with the benefit of digital stabilization and accommodative padding of the joint. I believe conservative methods can slow if not halt progressive lesser MPJ dysfunction. The key is in early identification of the condition and proper patient education.

Step-By-Step Pointers On Using The Suture And Button Technique

It bears mentioning that I prefer to avoid plantar approach incisions to this dissection as I think the hazards of that outweigh the benefit in the ease of exposure of the plantar plate.

Make a dorsolinear incision. Start over the distal aspect of the second metatarsal and extend it onto the digit beyond the proximal phalanx base. Identify and isolate the second MPJ. One can subsequently perform a dorsolinear capsulotomy to expose the metatarsal head and proximal phalanx, and the chondral surface of the metatarsal head. Then begin a frontal plane osteotomy at the distal aspect of the dorsum of the anatomic neck of the metatarsal, and make a cut proximal and plantar, creating a long plantar wing.

Translocate the metatarsal head proximally to achieve joint decompression. The metatarsal head will shift independently given the fact that its previously elongated condition loaded the metatarsal head and elevated the physiologic pressure there. The prevailing thinking is this intraarticular pressure causes the joint inflammation and chronic wear and tear that ultimately disrupts joint function, leading to symptoms. Surgical experience in osteotomizing a long second metatarsal demonstrates this phenomenon and underlines the importance of shortening the second metatarsal bone when attempting to correct MPJ dysfunction.

With the metatarsal head disarticulated, it is easiest to evaluate the plantar plate from this dorsal approach. In my limited experience with this procedure, the plate itself is not usually deviated in a direction commensurate with the subluxation of the digit. Homologous to the relationship between the first metatarsal head and the sesamoid apparatus, it is the metatarsal head that seems to be shifted out of position.8 Once one has decompressed the joint, the realignment of the metatarsal osteotomy restores the anatomic relationship between the plantar plate and the metatarsal head.

Once you have realigned the metatarsal head and re-established the coaxial orientation of the proximal phalanx and the metatarsal, the toll that subluxation has taken on the cartilage surfaces of the joint becomes apparent. The flattened condition of the lateral base of the proximal phalanx and the head of the metatarsal head is evident by the increase in lateral MPJ joint space, which can result from prolonged subluxation.

With this realignment complete, the focus shifts to stabilization of the ray, which is the final task in completing the procedure. Take note that there has been no violation of the digit itself and no digital incision beyond the level of the proximal phalanx. In addition, one has not performed bone resection, arthroplasty or arthrodesis.

There is a positive point associated with this technique. One may reduce chronic edema by avoiding soft tissue dissection and resection of bone in the small space of the digital compartment. This is an important difference in comparison to the more traditional forms of sequential reduction and digital stabilization that require a significant amount of trauma to the digit.

In addition, by using this suture and button technique to stabilize the MPJ and plantar plate, the surgeon may reduce or avoid the development of profound residual edema, referred to as “the sausage toe,” which is often the source of patient dissatisfaction after digital surgery.

Additional Insights On Suturing

The surgeon can achieve actual stabilization of the plantar plate with a suture and button technique. I have chosen to use absorbable suture in lieu of leaving a non-absorbable material in the small compartment of the lesser MPJs. If one employs a non-absorbable suture, the suture acts as a residual foreign body, potentially increasing the residual postoperative edema. From a purist standpoint, absorbable material is not permanent and the inflammatory reaction associated with it is limited by the half-life of the material versus its non-absorbable counterpart.

With the joint exposed and the metatarsal osteotomy complete and stabilized, one can direct attention to the compartment of the MPJ. Load absorbable 3.0 vicryl on a Keith needle. First, run the material alongside the metatarsal head at the level of the anatomic neck through the plantar plate and out the bottom of the foot.

Then extend the suture across the metatarsal neck and run it through the opposite side of the plantar plate, and out the ball of the foot. This suture lassoes the metatarsal neck and allows stabilization of the plantar plate beneath the metatarsal head.

In addition, the suture lassoes the phalangeal base over the extensor digitorum longus tendon (EDL). There is no tension along the digits despite loading of the forefoot. This is due to the virtual lengthening of the EDL tendon given the shortening of the metatarsal.

Prepare the suture and run it along the sides of the base of the proximal phalanx. Secure the plantar plate with each run of the suture medially and laterally. Secure the four free suture ends outside the ball of the foot to a sterile button using a chain of five or more hand ties.

In Conclusion

I am reporting this technique as a preliminary pilot project. There has not been a prospective controlled trial evaluating this technique. Further investigation and clinical follow-up is ongoing and I will report on this as new information becomes available.

Dr. Judge is a Fellow of the American College of Foot and Ankle Surgeons. She is in private practice at North West Ohio Foot and Ankle Institute, serving Ohio and Michigan. Dr. Judge is an adjunct faculty member at Ohio University and the Ohio College of Podiatric Medicine. She is also on the faculty for graduate medical education at Mercy Health Partners in Toldeo, Ohio.

For further reading, see “How To Detect Second Metatarsal Pain” in the January 2002 issue of Podiatry Today or “How To Address Key Biomechanical Issues With Second MPJ Injuries” in the April 2008 issue. To access the archives, visit www.podiatrytoday.com.

Comments

Later this week, we'll be posting a follow-up blog from Molly Judge, DPM, FACFAS. Dr. Judge will expound upon the suture and button technique for plantar plate stabilization and share some questions on the technique from colleagues at a recent seminar.

I liked the direct approach your procedure takes to this pathology. My question is how the suture affects the extensor digitorum longus (EDL). Does the tension of the suture cause damage to the tendon? How do you get motion in the joint postoperatively with the tendon tied down with the suture?

The underlying biomechanical cause of many cases of 2nd MTP joint dysfunction is first ray inadequacy. Most patients in the earlier stages of 2nd MTP joint dysfunction can be treated with orthotics, not surgery. Hypermobile first ray, forefoot supinatus can be treated via a first metatarsal head cut out, forefoot valgus posting when appropriate and a metatarsal elevation in the device.

I appreciate your input regarding 2nd MTPJ dysfunction. I agree with you wholeheartedly regarding the potential success of treating HAV with the benefit of orthotic devices. However, the 2nd MTPJ dysfunction has not responded equally well to that therapy. Once the instability has progressed and subtle subluxation and pain has developed, the need for an external splint and accommodative support of the MTPJ predictably provides pain reduction and stability to the affected joint. In my experience, stabilizing the 2nd MTPJ via metatarsal sling pad is far and away the best way to approach this lesser MTPJ instability and pain. The ADDED benefit of a formal orthotic device is an important one but doe not preclude the use of the metatarsal sling pad.

You make a valid point regarding the benefit of orthotic devices in the face of hallux abducto valgus and I agree with you that long-term management includes providing forefoot balancing. In my opinion, treating 2nd MTPJ dysfunction is a conservative issue by and large.

Unfortunately when patients are misdiagnosed, they often present to my office LATER having undergone numerous forms of treatment failures that include surgery. In my article, I emphasize the importance of the clinical and radiographic examination, and the need to exhaust conservative therapy. Only a few patients in my practice have ever required surgical intervention for this condition and I share that experience with the readers. The cases that I discuss in the cover story article on 2nd MTPJ dysfunction are the exception to the rule. In fact, the conservative method is very effective for 2nd MTPJ dysfunction in many cases.